To remedy the Commission's concerns, for the next five years Google proposes to clearly label promoted links to its own specialized search services so that users can distinguish them from natural Web search results, and display links to three rival services.

To deal with allegations that Google may have copied travel and restaurant reviews from competing sites without their permission (so-called "scraping" content) , it will also offer all websites the option to opt-out from the use of their content in Google search. Newspaper publishers already have the option to opt their content in or out of Google News service.

Finally, in its contracts with advertisers, Google says it will no longer include any obligation for customers to source online search advertisements exclusively from Google.

But some complainants are not impressed. "We will withhold final judgment on Google's proposals until we have had time to analyze them in detail, but we and others will be looking to see how they measure up to the even-handed principle standard. The early signs are that Google's proposals will fall far short of this minimum requirement," said Shivaun Raff, CEO of Foundem, one of the first to complain to the Commission about Google.

Time is also an issue, with many complainants believing that one month is not long enough to assess the remedies. "Google has obviously had plenty of time to test how these remedies will work in practice, and complainants and other third parties should be given the time and opportunity to do the same thing," said David Wood lawyer for the ICOMP group, which represents some of the complainants.

The Commission will take feedback into account in the Commission's final analysis. If it finds that the commitments offered by Google are sufficient, it will impose them legally and appoint an independent monitoring trustee to ensure they are properly implemented.

However if the remedies are not deemed sufficient, the Commission could still fine the company up to 10 percent of its annual global revenue ($37.9 billion last year).

In January, ICOMP filed a new complaint, under Article 101 of the Treaty on the Functioning of the European Union (TFEU), saying that Google attained its dominance by unlawful means "by illegally blocking rival search engines' access to customers and consumers and forcing its advertising and publishing partners to work with it exclusively."

Google also faces complaints from FairSearch, a group of 17 companies including Microsoft, Nokia and Oracle, which says the Internet giant was using Android to promote its own smartphone applications.